Wavepacket Solutions of the Klein-Gordon Equation

We find dispersion-free wavepacket solutions to the Klein-Gordon equation, with the only free parameter being the wavepacket velocity $\mathbf{v}$. These wavefunctions are eigenvectors of a velocity operator with commuting components which is symmetric in a certain scalar product space. We show that this velocity operator corresponds to a classical generator which may be obtained by a canonical tranformation from $\mathbf{x},\mathbf{k}$.